Liquid-crystal television and computer displays (LCD) are known in the art, for example, reference is made to U.S. Pat. No. 4,766,430, issued to Gillette et al. on Aug. 23, 1988, incorporated herein by reference. As disclosed in this patent, a select-line scanner selects one horizontal scan line at a time of a video signal (having an active portion of about 50 .mu.sec.) and a ramp voltage is applied through respective transfer gates to each vertical data line, thereby charging the liquid crystal pixels arranged at the crosspoints of the vertical data lines and the selected horizontal line. A 6-bit counter associated with each vertical data line, primed in accordance with the level of the particular one of the 64 different possible grey-scale brightness levels of the crosspoint pixel, is decremented to zero, at which point the transfer gate associated with that vertical data line is opened, thereby making the charge on the liquid crystal crosspoint pixel proportional to its proper brightness level. Thus, the counting rate of the 6-bit counter needs to be only about 1.25 MHz, i.e., the reciprocal of 50/64 .mu.sec.
Because amorphous silicon (aSi) is inexpensive compared to polysilicon, it is desirable to employ aSi for a television LCD on a chip, which also includes the control circuitry therefor. Due to the relatively large capacitive time constant of control-circuitry comprised of aSi transistors, it is not normally possible to operate a data-line counter at a rate substantially higher than the 1.25 MHz rate of the 6-bit counter disclosed in the aforesaid Gillette et al. patent. However, an effective rate of about 5 MHz is required to accommodate the 256 (8-bit) grey-scale level employed by NTSC television. In addition, the capacitance of each select line of the LCD, which constitutes the load of each stage of the select-line scanner, is quite large and requires a relatively high-power transistor to completely charge the select line during the relatively short (no more than about 13 .mu.sec.) non-active portion of each horizontal-line video signal. Again, the relatively slow operation of aSi transistors normally prevents such transistors from being employed in the select-line scanner of a relatively high-resolution LCD (e.g., a television display comprised of about 250,000 pixels per frame).